Nearly a month after Malaysian Airlines Flight 370 vanished, a team of Maryland engineers detected the pings from a flight data recorder that narrowed the search area to a more manageable yet still vast swath of the Indian Ocean.

Working from an Australian warship involved in the search, a crew of nine from Phoenix International in Prince George's County deployed a U.S. Navy listening device to the depths of the ocean in the hunt for a signal from the doomed jetliner's black box. Tapped by the Navy to assist Malaysian, Chinese and Australian officials in the search, the team and their equipment had flown from an office and warehouse in Largo nearly two weeks earlier.

More recently, as the black box battery likely faded away, the Phoenix team dropped an unmanned torpedo-shaped Bluefin-21 submarine into the sea to scan the uncharted depths with sonar.

And if the wreckage is found, another of the company's tools could trawl for the data recorder just as it did in 2011 as investigators unraveled the mystery of Air France Flight 447, nearly two years after it crashed in the Atlantic Ocean.

If there are answers to all the questions about the Malaysian flight's demise, it could be Phoenix's work that allows them to be learned. It is just the latest tragic mystery added to the list of the company's undertakings, which include multiple ventures into the bowels of the Titanic as well as searches for sunken treasure and even Amelia Earhart's plane.

"It's expensive, but when you think about the people who perished…," said Tim Weller, program manager for the company's commercial operations. "Understanding why it crashed saves lives, and ultimately, it saves money."

The search for the doomed jetliner reached its 45th day Monday, with no sign of the wreckage in a search area about 6 miles across, some 1,200 miles northwest of Perth, Australia. The Boeing 777-200ER with 239 passengers aboard, including three Americans, disappeared March 8.

The Australian ambassador to the United States said Sunday that Australian officials leading the search would decide this week whether to alter or scale back the effort.

It is familiar territory for the Phoenix team that joined the search a month ago amid more intense media scrutiny than the company's ever faced before. That work, combined with with contracts for underwater ship and submarine repairs, makes up about half of the company's business, with the rest from commercial clients searching for old shipwrecks, or oil and gas deposits.

The company is on-call for U.S.-led missions, getting as little as four hours' notice to send workers and equipment to Dover or Andrews Air Force bases for deployment. Called this time two weeks after Flight 370 disappeared, the Phoenix team flew out of Baltimore-Washington International Thurgood Marshall Airport destined for Perth.

Once on scene, the team joined the ships and aircraft scouring a huge expanse of the Indian Ocean west of Australia for pings from a small metal canister attached to the plane's black box. Unlike the others, they dropped a bright yellow sea-ray-shaped device from Australian Defence Vessel Ocean Shield far deeper.

The Navy device detected an apparent signal from the wreckage. While other detections were deemed unreliable, Phoenix's data on the Navy-owned tool helped narrow the search area.

"That's a unique vantage point to listen from," said Peter LeHardy, Phoenix's business development manager.

With the likelihood that the pinger remains powered fading, however, the team shifted its focus to the findings of Phoenix's unmanned submarine dubbed Artemis, for the Greek goddess of the hunt.

Phoenix engineers program the bright yellow submarine with a lawnmower-style route to survey the ocean floor, sending sound waves from two sonar devices on either side of the sub. The crew can't see the sonar images in real time as they are gathered, so GPS data is used to turn them into maps that are created after the sub surfaces.

The search is stretching the technology to its limit. The ocean floor there is about 15,000 feet deep, which is about as deep as its unmanned submarines work, but there are valleys in the region that drop as far as 20,000 feet. A map of the world depicting where the company's technology reaches shows a scattering of trenches in the eastern Indian Ocean among the few areas outside its capabilities.

It's a difficult mission that can prove risky for the equipment.

"People sort of don't understand that putting stuff in the ocean and getting it back is nontrivial, especially if it has the capability to wander off on its own," said Jules Jaffe, a research oceanographer at the Scripps Institute of Oceanography at the University of California, San Diego. "To really get it to work in the deep sea is not easy."

It's not uncommon for researchers to lose a piece of valuable equipment. On one mission into the Titanic, a robotic explorer was lost inside the famous ship's Turkish baths, Weller said. A custom-built submarine similar to Phoenix's Artemis was never recovered from the search for the Air France jet lost in 2009.

Phoenix bought the $4 million Artemis submarine in 2012, its first mission diving in the South Pacific for Earhart's still-missing plane.

Even something as large as a jetliner isn't easily found. Massachusetts-based nonprofit Woods Hole Oceanographic Institution conducted the search for Air France 447 using a set of unmanned subs, but it wasn't until a third search trip and 109th dive that the wreckage was found.

"It can be challenging, especially when you don't have a good map of the sea floor, which I think is how they're operating," said Mike Purcell, principal engineer with Woods Hole. "I'm certainly very glad when we were doing the Air France search, we didn't have the scrutiny these guys do."

Crews in such missions spend weeks at sea, constantly running searches, downloading and sifting through data, and troubleshooting problems that frequently arise.

"You're six days out of port; you can't call Radio Shack for help," Weller said.

If the submarine does find the Malaysia Airlines wreckage, a difficult search still could remain for the black box. After Woods Hole found the Air France debris in 2011, Phoenix, using a different type of submarine that more closely resembles part of a tractor, recovered flight recorders a month later. Crews take turns on 12-hour shifts, manning the vehicle from a tiny control panel inside a shipping container.

Phoenix, Woods Hole and Massachusetts company Hydroid Inc. are among the few players capable of exploring the ocean's depths. Jaffe said he expects that to grow, perhaps due to interest in oil and gas exploration, but companies like Phoenix are well positioned given their experience.

"I think it's only going to get more interest in the future, and their vehicles could be used for survey," Jaffe said. "From the oceanographic point of view, it's not a bad place to be."